Grinding machine



May 12, 1936.

Filed Dec. l, 1934 H. E PRUITT GRINDING MACHINE 3 Sheds-Sheet 1 May H2, 1936; H. EV PRUITT GRINDING MACHINE l, 1954 5 Sheets-Sheet 2 Filed Deo.

May 12, E936. H. E. PRUITT 2,4@709 A GRINDING MACHINE Filed Deo. l, 1934 3 Sheets-Sheet 3 1,7@ 5 l 122/2312@ if@ 1Z0 u e o 107 125 115 ,719123 135 Patented May 12, 1936 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a grinding machine designed primarily for the grinding of taps, but it is to be understood that the machine is to be employed in any connection for which it may be found applicable.

One of the objects of the invention is to provide, in a manner as hereinafter set forth, a machine of the class referred to to provide the pilot end of the tap with a chamfered portion of arcuate curvature circumferentially and longitudinally with respect to the tap.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine of the class referred to for expeditiously grinding each flute or land of a tap concentrically with respect to the axis of the latter, whether the tap be new or broken.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine of the class referred to including a grinding element having a concave corner acting as a grinding surface for producing a charnfered portion disposed upon oppositely extending arcs to provide a clearance at the pilot end of a tap.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine of the class referred to including coacting means for guiding the lead and clearance for a tap at one operation.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine of the class referred to having as a part thereof a selectable indexing mechanism for controlling the position of the lands with respect to the flutes whereby the cutting edges of the lands are ground concentrically with respect to the axis of the tap irrespective of the number of lands and utes.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine for the purpose referred to including an adjustable centering means for the work to be acted upon.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine for the purpose referred to for disposing the work to be operated upon at the desired angle with respect to an abrading element.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine for the purpose set forth with means for bodily shifting an abrading element relative to the Work to be operated upon when occasion requires.

A further object of the invention is to provide, in a manner as hereinafter set forth, a machine for the purpose set forth, means for vertically and angularly adjusting the Work holder to position the work in the desired position to be satisfactorily operated upon by an abrading element.

Further objects of the invention are to provide, in a manner as hereinafter set forth, a machine for the purpose referred to which is comparatively simple in its construction, strong, durable, compact, conveniently adjusted, thoroughly efficient when used, and comparatively inexpensive to manufacture.

To the above ends essentially, and to others which may hereinafter appear, the invention consists of such parts and such combination of parts which fall within the scope of the invention as claimed.

In the drawings:

Figure l is a front elevation of the machine,

Figure 2 is a top plan view of the machine,

Figure 3 is a longitudinal sectional view of an adjustable Work holding and indexing structure,

Figure 4 is a section on line 4 4, Figure 3,

Figure 5 is a detail in horizontal section,

Figure 6 is a section on line 6 6, Figure 1.

Figure 7 is a fragmentary View in side elevation of the adjustable holder structure for the abrading element,

Figure 8 is a section on line 8 8, Figure 2, and

Figure 9 is an elevation of a modified form of abrading element.

The machine includes a supporting structure I comprising a pedestal part I I, an upstanding xtension part I2 at the upper end of the inner side of part II and a horizontally disposed hollow support I3 disposed at right angles to the extension part I2.

The pedestal part II has a flat top I4 formed with an opening l5 and a pair of valigning spaced threaded sockets Iii. The extension part I2 is disposed at an outwardly inclination to that side of part l I with which it is formed integral with, and it is provided with a flat vertically disposed outer terminus Il against which is secured the inner end of support I3 by the holdfast device I8. The arrangement of the pedestal part, extension part and support relative to each other forms the supporting structure l0 of angled contour.

The support It has its top I9 provided With a lengthwise extending dove-tail tongue 20 (Figure 6) and a lengthwise extending centrally arranged elongated slot 2l (Figure 2) opening at the 50 inner face of the top l and upper face of tongue 20. The slot ZI provides a clearance for a gear Wheel 22 carried by a shaft 23, journaled in the sides of support I 3 below the top IS. A means for manually operating shaft 23 is designated 24 55 and which consists of a hub 25 formed with a series of equally spaced radially extending arms 26. The hub 25 is secured to one end of shaft 23 adjacent the outer face of one side of support I3. The other end of shaft 23 carries a stop collar 21.

Mounted upon the top I9 of support I3 is a slide 28 having its lower face formed with a dovetail groove 29 coacting with tongue 20 for connecting slide 28 to support I3. A rack 29a is anchored in the lower face of slide 28 which meshes with wheel 22 whereby on the operation of the latter in opposite directions the slide 28 is moved in a reciprocatory manner lengthwise of the top I8 of support I3. A gib 36 is disposed lengthwise of one side of tongue 28. A binding or retaining screw 3I for gib 30 is carried by slide 28. The gib and screw coact to provide a close sliding iit between the walls of groove 28 and the sides of tongue 28. The slide 28 transversely thereof between its transverse median and inner end is formed with a dove-tail groove 32 for slidably connecting thereon a bodily adjustable carrier 33 for a driven abrading or grinding element. The carrier 33 includes an upstanding block 34 inclining in a direction towards the inner end of slide 28. The lower face of block 34 is formed with a dove-tail tongue 35 which is slidably mounted in and ooacts with the walls of groove 32 for adjustably connecting carrier 33 and slide 28 together. The carrier 33 is bodily adjustable transversely of slide 28. A gib 36 is positioned against one side of tongue 35 and a binding or retaining screw 31 is mounted in slide 28, bears against gib 36 and coacts with the latter to provide a close sliding fit between slide 28 and carrier 33. The means for adjusting the latter relative to slide 28 consists of a rotatable adjusting bar 38 (Figure 6) formed of parts 38, 48 and 4I. IThe part 39 is of less diameter than part 48, is peripherally threaded, extends frorn the inner end of part 40 and threadedly engages with the wall of a socket 42 formed in block 34. The latter is provided with a bore 43 opening at one side of the block. IThe part 48 is arranged within and extends from bore 43. The socket 4I opens into bore 43 at the inner end of and is of less diameter than that of the bore. The part 4I is of less diameter than part 48. The junction of parts 39, 48 provides a shoulder 44. The part 38 is of less length than part 48 and the latter is of materially greater length than part 4 I. Anchored to the slide 28, as at 46, is an angle-shaped laterally extending arm 41 formed with a vertically disposed apertured branch 48 at its outer end. The part 4I of bar 38 extends through the branch 48 and carries a hand wheel 48. The latter and shoulder 45 abut branch 48. The junctionof socket 42 with bore 43 provides a shoulder 50. On rotating bar 38 the carrier will be adjusted transversely of slide 28. The shoulders 44 and 5I] coact for limiting the adjusting of the carrier 33 in one direction, due to the fact that bar 38 does not move transversely with respect to slide 28.

The block 34 (Figure 2) is provided with spaced aligning sockets 5I, 52 opening at their outer ends at the sides of the block 34 and closed at their outer end by apertured plates 53 anchored to block 34. The latter is formed in its upper portion with a bore 54 which opens into the sockets 5l, 52 and aligns with the apertures 55 in the plates 53. Extending through the bore 54, sockets 5I, 52 and apertures 55 is a driven shaft 56 for operating an abrading or grinding element 51 of circular form. The shaft 56 is of a length to extend laterally in opposite directions, with respect to block 34, as at 58, 58. The shaft portion 58 carries the element 51, a retaining disc 68 positioned against the outer face of element 51, a lock nut 6I for disc 60, a retaining collar 62 positioned against the inner face of element 51 and a spacing means 63 between a plate 53 and collar 62. The abrading or grinding element 51 is in the form of an apertured disc 51 of the desired diameter and thickness having the inner part of its outer edge cut away to provide a concave working surface 51 circumferentially thereof, acting to provide a chamfer on the outer end of the lands of a tap. The curvature of the chamfer 'being arcuate in transverse and longitudinal directions thereof. The shaft portion 59 is provided with a key 64 for slidably connecting the shaft 56 to its driving pulley 65. Within the sockets 5I, 52 are bearings 66, 61 respectively for shaft 56. These bearings are retained in said sockets by holding nuts 68 positioned thereagainst and threadedly engaging with shaft 56. The bearings are arranged against the walls of the sockets. The nuts 68 are of less diameter than that of the bearings.

Secured upon slide 28 and bodily moving therewith is a driving motor 69 for the pulley 65. The n means to be presently referred to for vertically adjusting the structure 14.

With reference to Figures l, 2, 5 and 8. The structure 13 includes an upstanding hollow body part 15 open at its upper end. The body part 15 includes a rearwardly extended base plate 16 for closing its lower end. The base plate 16 seats upon the top I4 of pedestal part II and is out out on its inner face rearwardly of body part 15 to form a chamber 11 (Figure 8) The base plate 16 extends laterally in opposite directions with respect to the the body part 15, as at 18, 19. The upper face of base plate 16 rearwardly of body part 15 has an upstanding rib 88 formed with a socket 8| opening into chamber 11. The base plate 16 is also provided with an opening 82 (Figure 8) which communicates with chamber 11 adjacent one side of socket 8I. The side wall of chamber 11 is arranged inwardly adjacent to the side, front and rear edges of the base plate 16. The latter between its side edges and the wall of chamber 11 is formed with a pair of spaced parallel slots 83 which register with the sockets I6 (Figure 8). Fixed to the wall of socket 8I in base plate 16 is the reduced upper end portion 84 of a vertical stub shaft 85. The latter has its lower end portion 86 revolubly arranged in the opening I5 (Figure 8). The shaft 85 is formed with a shoulder 81 which abuts the top wall of chamber 11. Fixed to the lower end portion 86 of shaft and rotatable in chamber 11 is a gear wheel 88 adapted when rotated to shift the structure 13 horizontally on and at an angle with respect to the top I4 of pedestal part II. The means for rotating the gear wheel 88 consists of a pinion 89 carried on the lower end of `a vertically disposed stub shaft 96 extending upwardly through opening 82. Attached to the upper end of shaft 98 is a handle member QI arranged over base plate 16 and which is employed for shifting shaft 98. The pinion 88 meshes with gear wheel 88. The base plate 16 is normally locked stationary upon pedestal part |l, and for such purpose a pair of like locking members 92 are employed. Each of these members 92 is formed of a threaded bolt 93 having an enlarged head 94 provided with a handle 95. The bolts 93 extend down through the slots 83 and threadedly engage with the walls of sockets l (Figure 8). The heads ..94 of members 92 are adapted to bind against the upper face of base plate 1B whereby, in connection with the bolts 93, when these latter are screwed home, the structure 13 will be held stationary upon the top of pedestal art ll. When it is desired to angularly adjust structure 13 with respect to the top of pedestal part ll, the bolts 93 are loosened and gear 88 rotatable, as at the shaft 85, is xedly secured to base plate 16, the structure 13 will be shifted relative to pedestal part when wheel 88 is rotated. When adjusting structure 13, it is not required to entirely remove the bolts 92 as the slots 93 offer the necessary clearance for adjusting structure 13 in opposite directions.

Mounted on top of body part 16 is a closure plate therefor formed with an opening 91 for the passage of a vertically disposed rotatable screw rod 98 employed for elevating and lowering the structure 113. The rod 90 is suitably connected to plate 10 so as to cause the vertical movement of said structure 14. The rod 98, at its upper end, is provided with a turning wheel 99 therefor spaced, as at |00, from plate 95.

With reference to Figures l, 2, 3, 4 and 5. The structure 14 includes a carrier l0| in the form of a vertical plate lill having an upstanding arcuate slot |02 in proximity to one side edge thereof. The plate |0i, at a point between its vertical median and its other side edge is formed with an opening |02' positioned on the transverse median of the plate. The latter is formed with a threaded bore |03 communicating with and leading from opening |02 to the said other side edge of the plate. The rear face of plate |0l' is formed with a pair of spaced oppositely disposed flanges |04 lengthwise thereof. The inner side faces of flanges |04 are oppositely beveled. The flanges |04 coact to form the rear of plate |0| with a dove-tail groove. Integral with the inner face of plate |0l between and spaced from the flanges |04 is an extension or boss |05. The latter extends into the body part 15of the structure 13 from the front of the latter and is formed with a vertically disposed threaded opening |00 for the passage of screw 98 which threadedly engages with the wall of opening |09. The front of body part 15 of structure 13 is formed with spaced vertically extending parallel flanges 15 having oppositely disposed beveled outer side faces. The

flanges 15 are positioned in the groove formedl by and coact with the flanges |04 for slidably connecting the carrier l0| on the front of the body part 15 of structure 13. A gib 1B is arranged against the inner side face of a flange |04, the latter carries a retaining screw 11 for the gib 13. The employment of gib 10 in connection with screw 11 provides for a close sliding lit between the flanges 15 with respect to iianges |04.

The structure 14 also includes a cylinder |01 open at each end. The cylinder is pivotally suspended from plate |9l, and for such purpose there is arranged in opening |02' the circumferentially grooved head |08 of a pivot member |09 having threaded engagement with the wall of a socket ||0 opening at the outer periphery of cylinder |01. Engaging with the wall of bore |03 is a threaded retainer which extends into the groove of head |08. The cylinder |01 is formed with a threaded socket l2 which aligns with slot |02. The cylinder |01 is angularly adjustable on head |08 relative to plate |0|. is held in its adjusted position by an angle shaped locking member ||3 which extends through slot |02 and threadedly engages with the wall of socket ll2. The member ||3 includes a large head I4 which binds against the plate |0| (Figure 5) when the member ||3 is screwed home whereby the cylinder |01 is held in its adjusted position relative to plate |0|'. The wall of cylinder |01 is formed with a row of spaced aligning openings ing from said openings are spring controlled latching devices |20, |2|, |22, |23 and |24. Each latching device includes a rotatable spring controlled piunger |25 having an enlargement |26 at its inner end and a head |21 at its outer end. Each latching device includes means, as at |28, for maintaining the plunger thereof retracted. Arranged within the cylinder |01 is a rotatable tubular holder |29 forming the body part of a collet retainer and having spaced sets of spaced sockets |30, |3l, |32, and |33. The number of sockets of the set |30 is six, that of set |3| four, that of set |32 three and that of set |33 two. The locking devices |2I, |22, |23, |24 coact with the sockets of the sets |39, |3l, |32 and |33 for latching holder |29 in its adjusted position. The enlargements on the inner ends of the plungers of the latching devices |2l, |22, |23 and |24 selectively coact with the sockets of the sets |30, |3|, |32 and |33. The locking devices |2l, |22, |23 and |213, sets of sockets and holder |29 are employed for indexing the lands of the tap. The holder |29 has an opening |34 which coacts with the enlargement |24 of the plunger |25 of the locking device |20 for retaining the holder or collet retainer |29 in its initial position prior to adjustment thereof.

The holder |29 has secured to one end thereof an interiorly beveled annulus |35 forming the head of the collet retainer and through which extends a collet |33. The head |35 of the collet retainer is or" greater diameter than the holder |29 and bears against one end of cylinder |01. The other end of the holder |29 is formed with a reduced peripherally threaded tubular extension |31. The stem of collet |33 is indicated at |38. The stem is tubular and is formed with peripherally threaded reduced inner portion |39. Extending into the holder |29 from the extension |31 is a tubular pull bar threads at its forward end for engaging the peripheral threads on the reduced inner portion |39 of stem |38 whereby the pull bar |40 and collet |35 are connected together. The function of pull bar |40 is to draw the collet |36 rearwardly to provide for head |35 of the collet retainer acting on the outer end of the collet to clamp the work to the latter. The pull bar |40 has a reduced rear end |4| for connection to a hand wheel |42. The pull bar |40, immediately adjacent the wheel |42 is formed with peripheral threads with which engages an adjusting nut |43 for the bar. The nut |43 is detachably secured from rotation. Carried by the forward end of the pull bar |40 is a work centering element |44 which extends into the stem of the collet. The nut |43 acts upon the pull bar |40 for shifting the latter relatively to the shank of the collet for adjusting the position of the element |44 lengthwise with respect to the collet stem.

The cylinder |01 |40 having internal Threadedly engaging with the extension |31 of holder |29 is removable locking means |45 which, when locked in position, abuts the cylinder |01 and in connection with the head |35 of the collet retainer prevents the shifting of the latter lengthwise relative to cylinder |01. After the nut |43 has been operated to adjust the position of element |44 it is secured in abutting relation against the rear end of extension |31 which prevents the shifting of pull bar |40 relative to the collet retainer.

When the holder |29 is free of the latching devices, the collet retainer, collet, work and pull bar are bodily revolved together the desired extent within cylinder |01 when occasion requires to properly position the work relative to the .grinding element. This can be accomplished When the locking means |45 is loosened.

The abrading element shown in Figure 9, indicated at |46, is in the form of a circular disc |41 having a convex edge |48.

With respect to the operation of the machine. 'Ihe tap to be 4ground is extended into and locked to the collet which forms an element of the combined Work holder and indexing structure 14 bodily carried by the suspending structure 13. The structure 14 is adjustable vertically and at an angle relative to the structure 13. After the tap has been locked to structure 14, the structure 13 is then angularly shifted horizontally upon and with respect to the top of the supporting structure |0 to about from ve to seven degrees so as to position structure 13 off-center with respect to the .grinding element 51. After the adjustment of structure 13 to the desired point, it is clamped solid upon the top of structure |0 and structure 14 is then adjusted at an angle relative tostructure 13 for the purpose of obtaining the desired lean on the tap. After the structure 14 has been angularly adjusted relative to structure 13 it is locked in its adjusted position. The grinding element 51 is then arranged so that the point vof the tap is directly over the concave working edge of said element. The tap is now set for grinding clearance. The screw 98 is now revolved in a direction to provide for the lowering of carrier |0| to an extent .whereby the tap will contact with element 51. The slide 28 is then reciprocated in a. direction towards and from the tap to cause element 51 to travel directly under the tap and act on the latter. After one flute of the tap has been acted upon, the other iiutes thereof will be successively indexed by structure 14 and successively acted upon by the element 51. After a grinding action has been completed on a flute, the carriage |0| is elevated, the tap turned, the follower flute indexed and the carriage |0| lowered to position the indexed flute for grinding action thereon by element 51.

What I claim is:

1. In a grinding machine, a support, a suspension structure mounted thereon and formed with spaced parallel slots at its bottom, a gear interposed between said support and said structure, a pinion meshing with said gear and positioned at the bottom of said structure, a shaft for the gear revolubly mounted in said support and fixed to .said structure, means for revolving the pinion to provide for the angularly adjusting of said structure relative to said support, releasable means extending through said slots and engaging in the support for locking the structure in its adjusted position, a structure vertically movable relative to and bodily carried with the suspension structure provided with a combined work holding and indexing mechanism capable of being angularly adjusted on a horizontal axis, a grinding element, and means for operating, supporting and moving said element towards and from the work held by said mechanism.

2. In a grinding machine, a grinding element structure arranged in juxtaposition to the work to be acted upon and comprising a rectangular hollow supporting means having a dovetail tongue on its top and a slot at the lengthwise center of the tongue, said tongue disposed lengthwise of, substantially of the same length as and having its sides spaced inwardly adjacent to the side edges of the top, a slide seated on said tongue and riding on the side marginal portions of said top, said slide being provided at its lengthwise center with a rack opposing said slot, a rotatable shaft extending transversely through said supporting means and provided intermediate its ends with a gear'engaging with the rack for reciprocating the slide; an upstanding support disposed transversely of the inner end portion of, seated in and slidably connected to the slide and disposed at an inclination towards the work, a grinder element, an operating shaft for said element, said shaft being carried by and extending from said support and carrying, at one end, said element and positioning the latter adjacent to one side of said supporting means, means carried by said support and slide for adjusting the support transversely with respect to the slide, a motor bodily carried with the slide, and an operative drive connection leading from the motor to the other end of and for said shaft, said drive connection being slidably connected to the said other end of the shaft.

3. In a grinding machine, a combined work indexing and holding mechanism, a vertically movable and horizontally revolvable carrier, an upstanding horizontally revolvable support for and having means for connecting the carrier thereto and for vertically moving the latter, said mechanism being disposed transversely of the carrier, an outwardly directed horizontally disposed pivot revolvably connected within the carrier and iixed to said mechanism to provide for the angularly adjusting of said mechanism relative to and independently with respect to the carrier and said support, a stationary supporting means for said support, means interposed between said supporting means and support, connected to the latter and in engaging in said supporting means for revolving the support horizontally upon said supporting means, spaced means carried by the bottom of the support andreleasably engaging in the top of said supporting means for locking said support from movement relative to the supporting means, and said mechanism and carrier having coacting parts for securing the mechanism in adjusted relation with respect to the carrier and support and to provide for said mechanism and carrier vertically moving together relative to said support and said carrier and mechanism bodily moving together with said support on the horizontal revolving of the latter.

HARVEY E. PRUITT. 

